1. Field of the Invention
The present invention relates to a silicon-containing preploymer, particularly to a 3D network-structured silicon-containing preploymer, with a terminal of hydrophilic chains, i.e. a silicon-containing preploymer with an internal section of silicon-containing chains and an external section of hydrophilic chains, which is applicable to fabricate silicone hydrogel contact lenses.
2. Description of the Related Art
In addition to stability, non-toxicity and deposition-proofness, PMMA (polymethyl methacrylate) has superior optical properties and is abundant in source and cheap in price. Therefore, PMMA is the first plastic material used to fabricate contact lenses. However, PMMA is disadvantaged by poor hydrophilicity and poor oxygen permeability, which impairs the application of PMMA to contact lenses.
PHEMA (poly(2-hydroxyethyl methacrylate)) proposed by Witchterle and Lim is the first hydrogel used as biomedical material. PHEMA is a 3D network-structured polymer, swelling but insoluble in water. PHEMA has been widely used in biomedicine, especially in contact lenses. However, PHEMA is disadvantaged in low balanced water content and poor oxygen permeability, which has long limited the application of PHEMA. Therefore, many researchers have developed copolymers of PHEMA and hydrophilic monomers to overcome the abovementioned disadvantages of PHEMA.
The related manufacturers had persistently studied and researched the ways to improve comfort of users wearing hydrogel contact lenses and finally developed a plasma-based surface modification technology. The manufacturers use the technology and hydrophilic materials to improve the hydrophilicity of the surfaces of contact lenses with the oxygen permeability of silicone hydrogel being preserved. However, the technology needs expensive equipment and complicated processes. Besides, the technology cannot achieve stable bonding of the hydrophilic material and the surface of the silicone hydrogel and thus cannot achieve uniform quality, stable yield and low fabrication cost.
Based on theories and many years' experience in the related field, the Inventor had been persistently devoted to studying and researching the abovementioned problems and finally developed a 3D network-structured silicon-containing preploymer to overcome the abovementioned problems. The principles and embodiments of the present invention will be described in detail below.